


Sex on the Beach

by NihilismPastry



Series: Laced and Bound [2]
Category: Undertale
Genre: Alcohol, Animalistic Sans, BDSM, Bara Sans, Bara!Sans, Beach Episode, Beast Tale AU, Beasttale AU, Big Sans, Biting, Blood, Dirty Talk, Dom!Sans, Dominate Sans, Drunk Reader, F/F, F/M, Female Reader, Fingering, Growling, Horny Reader, Lightly described reader, Master/Pet Play, Medical Science is Screwed Over, Papyrus is a cinnamon roll, Possessive Sans, Post Pacifist Route, Reader Is Not Frisk, Sans is knotty, Shitty Puns, Short Lived Fluff, Small reader, human reader, knotting kink, part of a one-shot collection, reader is chubby, voyerism
Language: English
Status: Completed
Published: 2016-08-25
Updated: 2016-08-25
Packaged: 2018-08-10 16:24:20
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,037
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7852465
Author URL: https://archiveofourown.org/users/NihilismPastry/pseuds/NihilismPastry
Summary: <blockquote class="userstuff">
              <p>Sans' mate drags him to the beach for their 'Beach Special'. He has no problem with it, really. He just didn't like it when she was an utter cock tease.</p>
            </blockquote>





	Sex on the Beach

**Author's Note:**

> It took a day longer to pump out the chapter, so hopefully you guys like it a bit? Oh, and has anyone listened to Pony by Far? That just screams Beasttale Sans.

Sans had accepted many things about his mate. Like how she hated ketchup, refused to participate in electricity play, and her love for waking up early. While he would be content to spend the entire day in bed, she was up at the crack of dawn humming a tune while getting dressed. On the occasions she managed to wake him up, she always annoyed him. Sometimes he'd drag her back into bed and thoroughly exhaust her again, others he'd ignore her in hopes she'd leave. However he had no options for either as she straddled his spine, one hand caressing his ribs, the other waving her phone. "Sans, guess what!"

"You're gonna suck me off?"

"After what happened last time, no." She pressed a button on her phone, revealing a text from Papyrus that came in ten minutes ago. "We're going going to the beach, remember!"

Oh yeah. Undyne had recently found a job at the natural history museum as a night guard. She had wanted to go to a beach to celebrate, and had asked Sans to be their ride since transportation for monsters was still a work in progress. He'd accepted of course, but why in the hell was his mate trying to get him up while it was still dark out? He thought he'd be getting a break since Papyrus was sleeping over at Undyne's.

He blinked warily and yanked the phone out of her hand. She yelped, but made no move to fight him as he flung the blue device onto her bedside table. "If I teleport everyone, we'll be there in seconds. So why're ya waking me up so early?"

"Because we've gotta pack and stuff." She shifted, one of her thighs brushed against his spine, causing a low growl to rumble through him. Huh, maybe she'd do that again. "I would've done it last night, but I got back from the lab late."

 He shut his eyes and sank back into the bed. "Then go pack."

"I need help." Her voice had gone up in pitch. Oh god, his mate was like a puppy. A very needy puppy that wouldn't just let him sleep. "Come on, I'll let you pick my bikini~."

An eye socket opened to stare at her. "How much time until they come over?"

"We're supposed to leave about eight-Ah!" He yanked her down and licked her neck, his tongue prodding the relatively new scabs on her skin. Surprisingly she didn't taste like a raspberry chemical cocktail."S-Sans it's still early, what about the neighbors?"

"Guess ya better keep that mouth shut." He tore her underwear off and plunged two fingers into her pussy. "Now spread those legs for me so I can make your other mouth scream."

* * *

After a quick and hard fucking, Sans bathed his mate and let her do most of the packing while he fell back to sleep on the couch. Occasionally she'd wake him up to get anything that was too high for her to reach, but she completed everything by herself for the most part. At 7:55 the door was ripped open, and a tall skeleton ducked his head as he entered the house. "GREETINGS BROTHER, HUMAN, ARE YOU PREPARED FOR THE BEACH DAY SPECIAL?"

"Sure, bro."

His mate adjusted the dress she wore over her bikini with one hand, while the other was tapping at the checklist she made with her phone. "Uh huh, I'm just making sure the stuff's packed one last time. Everything is always more expensive at the boardwalk."

Sans opened up a socket from his place on the couch. "Don't worry 'bout it, we're supposed to be celebrating."

"THAT'S RIGHT, HUMAN. WHILE I APPRECIATE YOUR FRUGALITY, WE ARE SUPPOSED TO RELAX AND ENJOY OURSELVES TODAY." 

His mate pursed her lips, but didn't have a chance to argue as the door burst open. Undyne waltzed into the room with a blushing Alphys in tow. Both looked liked they raided a beach shack with their hats, sunglasses, and other beach wear. "Hey losers, ready for some fun in the sun?" Undyne hugged her girlfriend close to her chest. "Alphys hasn't stopped talking about it."

Alphys looked damn near giddy as she blushed at Undyne's confession. Since coming to the surface the scientist had been swamped with the lab at the Monster Integration Bureau. Seeing his best friend smile so wide relaxed him just a bit. He sat up and got off the couch, his magic already sparking and expanding. "We ready to go?"

Once he got the okay he focused his magic. "You guys might wanna close your eyes." It slithered into the cracks of reality and split the world apart, creating a giant gaping hole in the ground. It sucked them down through the void without a sound, and deep into the pits of darkness. The putrid smell of rot and decay filled the air, and millions of eyes stared him down. He ignored them while he dragged them further and further until he felt the place he had sent his magic. There was a loud crack and the world was ripped open again, this time in a place that smelled heavily of salt and burning wood. "Kay, we're here."

He watched as the others opened their eyes, mouths hanging open in surprise. None of the monsters present had been to the beach before. It was only recently that monsters, outside the royal family, could leave the city. So seeing the wide expanse of murky blue water, trash filled sand, and the cluster of white washed buildings was a new experience.

Undyne screamed and ran towards the water, dragging Alphys behind her who dropped their bag in surprise. "FUHUHU! Last one in the water is a rotten spider cider!"

Papyrus stopped gawking and set his things down neatly before he ran off after them. Shouting a battle cry as he easily managed to out run the couple. A soft smile curled onto the skeleton's face as he watched his brother. It was nice to see his brother be able to just run around and be excitable without having to worry about his size. It'd been awhile since Papyrus was able to do something as simple as that, and sometimes Sans worried that Papyrus really wasn't happy 'upstairs' because of it. 

"Wow, that was only the third most painful thing I've ever done." Sans's attention snapped over to his mate, panic rising in him as he looked her up and down for abnormalities. She was kneeling next to their bag and was fishing for something. "Think I'm gonna skip swimming for now." She flinched when he knelt down next to her, his fingers digging under her dress and face close as he continued his search. "Um, you alright."

No, she smelled like rot and magic. He hated the smell of the void, having it cling to his mate only served to piss him off. "Did it hurt, or are ya being sarcastic?" 

She leaned into him, her hands pausing in her task. "It hurt, but it was in my soul, not anything physical. Almost like when my soul was ripped out so they could encase it in the incubation barrier when we were teathered." Her hand clutched her chest. "My soul wanted to leave, but the barrier wouldn't let it I guess." 

She shrugged and went back to their stuff. Sans watched her for a few moments before laying out on the sand. While it would suck having to shake the sand out of his jacket and shorts, he wasn't interested in unpacking everything. He fully intended to catch up on the sleep he missed out on this morning, maybe play a game with his bro, and watch his mate run around in her swim suit. He cracked an eye socket open when he heard cloth snapping in the air and a breathy sigh. 

His mate was now laying on a towel, her dress off and her green bikini showing for all the world to see. Her eyes were shut and her fingers laced over her chubby stomach. It was a newer feature she acquired since moving in with him and his brother. Apparently pasta and large portion sizes were bad for humans. Speaking of which..."Hey, aren't ya supposed to wear sun liquid?"

"Lotion." She corrected. "And no, my skin is dark enough that I don't really need to. I mean, it's the healthy thing to do, but I'm too lazy." She yawned and stretched a bit, her tits bouncing with the movement. "Guess I learned something from you."

He decided to accept the answer. Half the time he was too lazy to do much of anything anyway. That left him the next hour or so to sleep in relative peace, with wet dreams as his reward.

* * *

By midday the beach had become crowded. Sans had woken up recently thanks to the noise and chemicals in the air. He was currently standing in the shallows, half assing a game of Marco Polo with the others. In most cases Sans half assed most things, but this time he had more of a reason. Swarms of humans were playing on the beach, most of them keeping a good distance from the monsters. He had seen more than one sneer at them when they got too close, or had gone to the life guard to complain. He would be damned if someone ruined his brother's good time, and would deal with the problem if it arose.

"Got you~." His body stiffened when he felt fingers ghost over his spine. He twisted around, tail lashing out, and a growl rumbling in his chest. He knew it was his mate, he could pick her voice out in a crowd, but he was on edge. She seemed to realize it too, because instead of getting huffy, she removed her hands but remained close to him. "You wanna keep playing or are you ready to head back to the beach?"

He just shrugged. He was uncomfortable with either at this point, there were humans swarming everywhere. "Depends on what bro wants to do."

Papyrus was a good twenty feet away, but seemed to have heard his brother perfectly. "WELL, I AM GETTING HUNGRY. PERHAPS WE SHOULD HALT THE ACTIVITIES FOR A MOMENT AND EAT." 

Undyne nodded. "Yeah, sounds cool. We can break out the drinks too, how's that sound, babe?"

"S-sounds like fun." Her eyes widened as she thought of something. "Maybe we could play a d-drinking game?"

"Oh God, this is going to be so much fun." Sans's mate began the trek back to the beach, the others hurrying behind her. 

It took a few minutes to unpack the alcohol, but eventually everyone had a jug in their hand and was downing the stuff to a ridiculous game of 'never have I ever'. After only three rounds Sans noticed his mate was already becoming tipsy. Not all that surprising, she had the alcohol tolerance of a whimsum, but it wasn't normal for her to get that smashed that quickly.

"What are you drinking?" He asked after she took another sip after Alphys's question. 

"Sex on the Beach." His magic sparked to the words alone. "It's yummy."

Undyne laughed at the statement. "What kinda drink is that? Sounds like a stupid flowery drink a light weight would sip."

"I-I think it sounds kinda romantic." Alphys countered, her yellow scales were blazing a bright orange now as she glanced at Undyne. 

"It's yummy and vodka-y and..." Her eyes narrowed as she tried to explain it, but nothing seemed to come to mind. "I dunno, it's just good. I should totally get my friend to make you guys some." She shifted to sit on her knees. "Maybe we can steal a keg from a bar around here! Then mix it up? Yeah, you gotta mix it."

One of Papyrus's large hands came down and carefully took the mason jar from her. "PERHAPS THAT IS ENOUGH FOR NOW, HUMAN."

"Awe, but it's good!" She turned to look at Sans. "I can have it right, I don't even feel drunk." 

Personally, Sans liked the idiot side of his mate. All of the stupid things she said made wonderful blackmail. However she also made stupid decisions, and those were harder to keep under control in such a public space. "Listen to Paps, baby girl. Your common sense goes to shell when you're drunk."

Everyone in the group moaned at the display, while Alphys just giggled at the display."Y-you sound like her Dad, not her m-mate." 

Sans just grunted, but glanced down at his mate. She was now resting her upper body on his femurs, watching a group of kids play volleyball. Her ass was at the perfect angle to spank, and her back was arched just right. Damn she was such a tease.

* * *

 

As the day wore on the others eventually packed the alcohol back up and went back into the water. Undyne announcing that they should explore a bit, while Alphys said she was going to stay in the shallows to find seashells to bring home. Papyrus had went with Undyne of course, hoping to find a new island and claim it for King Asgore. Sans remained behind with his intoxicated mate, watching her shift from her stomach to her back.

Now her stomach was bare to him and her legs crossed. Her chest was popped upwards, as if she was trying to get him to pay attention to her tits. (Joke's on her, he was always paying attention to them.) She was staring at the sky now, her face still flushed, but her eyes held a soft expression that was rarely present. One of his hands reached forward and carded his claws through her thick curls. A soft hum escaped her lips, but she didn't push him away.

He actually treasured moments like this. Moments where he could pretend a reset wasn't on the horizon, that the humans didn't want them back under the mountain, or that he wasn't going to somehow kill his mate. It was peaceful, and that's all he could ask for.

"Hey." Sans looked up from his task, a glower in place as a lanky male human walked up to them. His skin was slathered in something white that smelled heavily of chemicals, obscuring most of the dark skin underneath. "What are you doing to that girl?"

Said girl was snapped out of her day dreaming as she sat up. "Huh?"

Sans curled an arm around her waist. This wasn't the first time humans had stuck their noses where they didn't belong, and Sans had to bit it off to get them to back off. "Ya need something, bud?"

"Yeah, I need you to leave that girl alone." He gestured to his mate. "She's drunk and you're taking advantage of it. That's pretty sick, isn't it?"By now a few people were paying attention, but most continued with their business. No one wanted to risk fighting a monster.

Sans opened his mouth, but his mate was already standing up, hands on her hips and leaning forward giving the guy an eyeful. Sans shifted in the sand, his body tense as his mate went on a rant. "I'm not drunk! Coming over here and making assumptions like a...a...stalker!" She jerked her head when she remembered the word. "Yeah, you're pretty creepy."

"No, what's creepy is how you're hanging all over a skeleton. Yeah he's a monster, but you can't bang him." Both humans ignored the low growl from behind them. "Do you have anyone here with you? I can take you home if you don't-"

"I'm fine!" She had raised her voice now. "I go home to Sans every night, because I live there. He's my family you know, kinda husband, but really not." Her face had a red tinge now. "And we do fuck! One time I gave him a blow job and he damn near knotted my throat, but it was so hot too."

By now Sans was standing up. Anybody who still held interest in this wassuddenly acting far more discreet. The male human's jaw trembled, but he didn't back down. "She needs to come with me, there's something wrong with what you're doing."

He grabbed his mate and held her close, one hand gripping her tit the other tilting her head to the side. While staring directly into his rival's eyes, he leaned down and a greenish yellow tongue traced over her neck. Surprise eased on the human's face, but it morphed to utter fear when he bit down. Blood rushed into his mouth and down her swimsuit. It was hot and sticky, and tasted better than it smelled. His mate's back arched and her toes curled into the sand, there was the quiet moan of his name on her lips. She was enjoying this, of course she would, she was his after all. He had trained her to accept all of his bites, and to even love them. She loved being ruined like this, and the look of pure shock on his rival's face proved it too. He slowly edged his teeth from her muscles and gripped her body a bit tighter. "She belongs to me, human. Get it?"

The human looked helpless as his mate writhed against him, keening for more. That's another thing Sans loved about his human: She was a horny drunk. The rival human backed away, hands up and shaking his head. "Stupid monster fucker."

Sans just chuckled at that as he sat back down, he really had no idea. He glanced back to his mate, she was rubbing her thighs together with a thick blush on her face. "Saaaans."

"Ya horny now, baby girl? You wanna take my cock with all these people around? Have my knot inside you while people stare?" His claws trailed up her thigh. "You think you earned it after being such a cock tease?"

She nodded. "I want it, Master. Please?"

"Nah, I don't think you've earned it." He leaned in closer to her, his fingers slipping under her bikini shorts and into her soaking wet pussy. "But if you keep begging, I'll think about it."

**Author's Note:**

> I'll be honest, I didn't like this chapter. Hopefully you guys do, because I think it's garbage. But then again I'm just hard on myself, so maybe it's decent. Just let me know. Oh, and the title was a pun.
> 
> Here's my tumbler if you wanna send in a request. http://nihilismpastry.tumblr.com


End file.
